CD8+ lymphomatoid papulosis and its differential diagnosis.

We describe 5 cases (4 males, 14-43 years old; 1 female, 61 years old) of primary cutaneous T-cell lymphoproliferative lesions expressing a CD8/granzyme/CD30-positive phenotype. Four cases were compatible with lymphomatoid papulosis (LyP) based on the clinical course, which was recurrent asymptomatic papular nodular lesions over years responding to methotrexate; granulomatous inflammation and lack of other inflammatory cell elements were characteristic. In 1 case, an initial erroneous diagnosis was made of aggressive epidermotropic CD8+ T-cell lymphoma. The fifth case in this series was first interpreted as representing primary cutaneous anaplastic large cell lymphoma but was later recategorized as primary cutaneous aggressive epidermotropic CD8+ cytotoxic T-cell lymphoma owing to the extent of extracutaneous dissemination, including testicular involvement and disease progression despite chemotherapeutic intervention. Although all cases of LyP showed sharp cytoplasmic membrane staining with perinuclear Golgi accentuation with CD30, the recategorized case of aggressive epidermotropic CD8 cytotoxic T-cell lymphoma manifested only a weak cytoplasmic staining pattern. CD8 LyP defines a distinctive entity with characteristic light microscopic and phenotypic findings and has a predilection for young males. CD30 expression can occur in other forms of CD8 lymphoproliferative disease unrelated to primary cutaneous anaplastic large cell lymphoma or LyP.